1. Field of the Invention
The present invention relates to an inkjet recording apparatus having a suction recovery unit configured to maintain a discharge state of a recording head for discharging ink for recording.
2. Description of the Related Art
In an inkjet recording head for discharging ink for recording, bubbles grow in a flow path from an ink tank to a discharge nozzle, and in a liquid chamber. When the bubbles reach the discharge nozzle, the ink is unable to be discharged, resulting in a poor image. To solve the problem, conventionally, a suction recovery operation for forcibly discharging the bubbles from the flow path by blocking the nozzle side of the recording head with a cap to reduce the pressure is regularly performed.
The suction recovery for removing the bubbles is called timer suction in which the timing of the suction operation is controlled according to the elapsed time since the last suction operation. The time to the next suction recovery in the timer suction is set such that the bubble growth amount in the flow path does not cause the discharge failure. However, it is known that the rates and amounts of the growth of bubbles vary depending on the usage environment of the inkjet recording apparatus body and the elapsed time since arrival suction. Accordingly, if the time from the last suction operation to the next suction operation is set to constant, the suction may be performed too often or suction failure may occur by the time the next suction operation is performed.
To solve the problems, the following known techniques are discussed. Japanese Patent Application Laid-Open No. 2010-52393 discusses a configuration for correcting a count value of elapsed time by acquiring a temperature of a recording head at regular intervals such that the count value increases as the temperature increases because bubbles in the head flow path grow faster as the temperature increases.
Japanese Patent Application Laid-Open No. 2008-62450 discusses a configuration for increasing an interval of timer suction as the accumulated number of recovery processes in the timer suction increases because the growth of bubbles becomes slow as the elapsed time since ink filling into an ink flow path increases.
Japanese Patent Application Laid-Open No. 2010-52393, however discusses a technique in which the correction amount of the elapsed time count in the timer suction is uniquely determined by the absolute value of the temperature at the temperature acquisition timing. Accordingly, the suction operation is performed at the regular intervals as long as the temperature is constant. However, this does not match the actual phenomenon that the growth of bubbles becomes slow with time from the time the ink is filled into the ink flow path discussed in Japanese Patent Application Laid-Open No. 2008-62450. In other words, the suction frequency becomes too high after the growth of bubbles becomes slow.
In Japanese Patent Application Laid-Open No. 2008-62450, the time interval is set based on the result of study in a high-temperature environment in which the rate of the growth of bubbles is high. The description lacks the concept that the rate of the growth of bubbles varies depending on the temperatures of the recording head discussed in Japanese Patent Application Laid-Open No. 2010-52393. As a result, when the inkjet recording apparatus is used in a room temperature environment, the suction timing becomes too early with respect to the amount of bubbles, and the suction frequency unnecessarily increases. Further, when the number of times of the timer suction operations increases, and the temperature in the usage environment of the inkjet recording apparatus increases after the interval of the timer suction is increased, the growth of bubbles may become faster than expected. As a result, a discharge failure may occur before the next suction timing.